Oil extraction from the seabed is now substantially more difficult than hitherto, and operators are now forced to follow a ‘brownfield’ strategy and extract oil from poorly yielding fields. As a consequence a low-cost inflow control valve to manage flows in existing, as well as future multi-lateral installations, is now called for. Additionally environmental and economic considerations, both sub-sea and on the surface, make it increasingly important to have a capability rapidly to shut off flow in the event of pipeline leak or rupture.
Pipes may range in diameter from a few inches to more than three feet. Typically pipes bringing oil to the surface are 5″ inside diameter, and inflow control valves may be slid into position along such a pipe and secured in place adjacent an opening in the pipe wall it is to control. In other applications where the valve is to control flow along a pipe, the valve may be installed at the time of pipeline construction, or may be fitted subsequently, within the pipe.
Previously suggested solutions have involved relying on a hydraulic line to operate a valve associated with a pipeline. However, such a line can only function effectively over a limited distance.
The present invention seeks to provide an actuator which is able to hold its position using minimal energy.
The invention also seeks to provide a valve and actuator combination which will operate in an adverse environment in remote locations where there is only limited availability of electric or hydraulic power.
Furthermore, the present invention seeks to provide an actuator, and a valve and actuator combination which can be fitted into and moved along a pipe for positioning as required, in which energy is stored locally to assist operation of the actuator and therefore the opening and closing of the valve.